Electric discharge device



July 10, 1928.. 1,677,000 v D. M F. MOORE ELEdTRIC DISCHARGE DEVICE Fil ed March 5. 1921 Daniel mc Farland Tfloore;

by M4 His Attorney.

Patented July 10,

nmm McFARLAN moon, or new omen. finw mnsnr. ASSIGNOR mo GENERAL ELECTRIC comram, A conronuron or NEW You.

ELECTRIC- DISCHARGE DEVICE.

Application 111m much 5, 1921. Serial in. 449,700. V

The present invention relates toelectric discharges between electrodes in gases and its main object is to provide a simple direct method and apparatus for startin an are between electrodes in an enclose space. Prior to my invention it was found necessary to provide enclosedarc devices with special starting mechanism, such, for example, as high potentials, electrode heating circuits. ionizing devices within the bulb, or the like, which usually required auxiliary electromagnetic switches, cutouts and the like.

In accordance with my invention, electric are devices, for example, lamps, rectifiers, or the like, are provided in which an arc may be started by the simple connection to a source of electric current. Devices embodying my invention preferably are provided with a filling of a highly conductive gas, such as helium or neon, in which a glow discharge may be produced at a moderate voltage, that is, gas of low dielectric strength. These and other aspects and advantagesof my invention will be more fully explained in the following specification taken in connection with the accompanying drawing in which Fig. 1

shows somewhat diagrammatically a' lamp embodying my invention; Fig. 2 illustrates a rectifier constructed in accordance with my invention; Figs. 3 and 4 illustrate modified circuit connections which may be used with devices embodying my invention, and

Figs. 5 and 6 illustrate modified electrode structures.

The novel features of my invention will be pointed out with particularly in the appended claims.

The lamp illustrated by Fig. 1 comprises a bulb 6 shaped much like the usual incandescent lamp and containing electrodes 7, 8, carried by the ends of supports 9,10, which are sealed into a stem 11. The electrodes 7, 8, consist of refractory metal, pref readily heated to incandescence, as herein-.-

after more fully described.

In the particular form of lamp shown in Fig. 1, the electrodes may consist of tun sten wlre having a diameter of .010 close y wound in a helix of about 15 'turns on amandrel of about .035diameter. The gap between the electrodes 7, 8, may be' about 4 th of an inch. The electrode supports 9 p and 10 may consist of tungsten of about .060" diameter. They are sealed into the bulb 6 in any well understood'manner, for example, these wires 9, 10 may be connected to special sealed-in conductors consisting of nickel-iron alloy and coated with copper, as now well known in the incandescent lamp.

art. The bulb 6 is filled with a suitable atmosphere which preferably consists of neon, helium, ora gaseous mixture containlng neon or helium; although other gases such as argon or nitrogen may also be used. I prefer to use agaseous filling consisting of a monatomic gas, such asneon, or neon Wltl1 an admixture of about 20% helium,

which is introduced after the bulb has been well exhausted and freed from water vapor according to methods now well understood. I prefer to use a pressure of about millimeters of mercury altho the pressure within the bulb may be varied within wide limits,

depending upon the character of the electrodes and the nature of the discharge which is desired. a

Supply conductors 12, 13, connecting the terminals of the lamp to a suitable source of alternating or direct current, as represented by the mains 14, contain a series resistance 15, and a switch 16. When the mains 14 supply direct current, say, at about 220 volts, the series resistance 15 should represent about 280 ohms.

Upon closing the switch 16 there first appears surround ing the electrodes 7, 8, an electric glow ,or

corona discharge oflight having the characteristic-neon color with a current of about .15 amperes flowing in the circuit. The amperage of the current steadily increases until at about'.30 amperes the diffuse corona has disappeared and the electrodes'become centers of spheres of intense whitish colored light. At this stage the electrodes are heated above redness, the current continues to rise and the electrodes become more highly heated. At about .50 amperes the spheres of light surrounding the electrodes 7, 8, lose their prominence and a very instense white arc appears in the gap between the electrodes. This arc continues to operate invided a reactance device having a win ing in series with the lamp on a magentic core 16. As the amperes coming through the lamp increase the voltage drop across the terminals of the reactance windings 15 increases.

The are device shown in Fig. 4 is connected to the secondary winding 18 of a transformer, the primary winding 19 of which, is supplied from mains 14:. The core 20 of the transformer is designed to have a relatively large leakage flux, the transformer being in general so designed that the open circuit voltage is materially higher than the operating voltage. This transformer elliciently reduces the voltage impressed upon the electrodes 7, 8, with little loss of energy as the current flowing through them in creases.

In Fig. 2 I have shown a rectifier embodying my invention in which the cathode 22, consists of a helically wound tungsten wire of relatively small mass, both terminals of which are connected to a supporting wire 23 sealed into the wall of the envelop 6 in the usual manner. The anode 24 has a mass and heat dissipating capacity suificiently great to operate at a temperature too low to act as a seat of an are. When the switch 16 is closed a glow discharge occurs between electrodes 22 and 24 which causes the cathode 22 to be heated to inca-ndeseence, as already described in connection with Fig. 1. As the current increases the voltage is automatically lowered by the inductance device 25, which has been dia rammatically shown as a. simple coil, whic may have any suitable form. The are between electrodes 22 and 24 is maintained by the half waves of current which have a negative polarity with respect to the electrode 22. The heat generated by the discharge through the gaseous filling in the bulb 6 may be utilized to produce mercury vapor from the mass of mercury 26. As the heavy mercury vapor in the device shown in Fig. 2 displaces the filling of neon or other suitable gas into the upper part of the bulb 6, the are continues to operate in the mercury vapor.

Althou h I have and 4, onl invention,

shown in Figs. 1, 2, 3 y helical electrodes embodying my I wish it to be understood that the form of these electrodes may be varied without departing from my invention; for example, in Fig. 6 I have shown a form of electrode in which the heat from a helix 7 aids a larger mass of tungsten 8 to become heated, and Fig. 5 shows an electrode consisting of four adjacent helices, the free ends 28 of which are twisted together and joined to a supporting wire 29. These helices may consist for example, of 15 turns of closely wound .010 tungsten wire wound upon a mandrel .035 in diameter. Other variations can be made but less starting voltages will be required when the electrodes are provided with cavities or their equivalent.

What I claim as new and desire-to secure by Letters Patent of the United States, la

1. The method of starting an electric arc discharge in a gas between closely adjacent electrodes constituted of conducting material one of which comprises a body of closely adjacent conductors of small section to facilitate the production of corona which consists in initially impres=ing upon said electrodes a potential sullicient to produce a glow discharge therebetween, maintaining such glow discharge to bring said small conductors to incandescence and increasing the current flowing between the electrodes.

2. An electric arc device comprising a sealed receptacle containing a gas having moderate voltage breakdown characteri tics, refractory metallic electrodes supported in said receptacle adjacent each other with a relatively short discharge path therebetween, one of said electrodes comprising a body of closely adjacent conductors of small section to facilitate the production of a glow discharge between said electrodes at relatively low potential difi'erence therebetween, and

circuit connections to said electrodes arranged so that each electrode carries current and only such current as flows between said electrodes during the starting of a discharge between said electrodes.

3. An electric arc device comprisin a sealed receptacle containing a gas having moderate voltage breakdown characteristics, electrodes supported in said receptacle adjacent each other with a relatively short discharge path thcrebetween, one of said electrodes comprising a body of closely adjacent filamentary conductors of small section to facilitate the production of a glow discharge between said electrodes at relatively low potential difi'erence therebetween, said receptacle being provided with a single pair of circuit terminals connected respectively to said electrodes.

In witness whereof, I have hereunto Set my hand this 3d day of March, 1921.

DANIEL MCFARLAN MOORE. 

